This invention pertains to log-handling apparatus, and more particularly to a device which functions to separate laterally fed logs for transmission end-to-end, and one at a time, to an off-bearing conveyor. While there may be many applications where such a separating device is useful, the device disclosed herein will be described in the setting of a sawmill, at a location just upstream from a log debarker.
In the usual sawmill, logs which are brought in for cutting into lumber, are transferred from a log pond to a conveyor which is intended to transport them, one at a time, into processing machinery such as a conventional log debarker. Typically, logs which are furnished this conveyor arrive side-by-side, and must be separated in some suitable fashion so that only one log at a time arrives at such machinery.
In the past, several kinds of lateral log separating devices have been made available, which are intended to accomplish the goal of one-by-one log feeding. For example, two such devices are disclosed in U.S. Pat. Nos. 3,502,191 and 4,245,735, both issued to Antti Valo.
A general object of the present invention is to provide an improved and unique lateral-transfer log-separating apparatus which offers reliable separation of laterally adjacent logs whose diameters fall within a predetermined range of diameters, and which, therefore, takes care of the problems heretofore experienced with conventional separating apparatus.
Another object of the invention is to provide such apparatus which is relatively simple and maintenance free in construction.
Still another object of the invention is to provide apparatus of the type just generally outlined, which can be installed in existing sawmills as a ready replacement for related prior-art apparatus, without the requirement for any major mill modification.
According to a preferred embodiment of the invention, the proposed apparatus includes, on a pair of side-by-side displaced, substantially parallel shafts, at least two longitudinally displaced pairs of adjacent discs, which, together with their mounting shafts, are driven to perform reversible cyclical counter-rotation, in plural ongoing operating cycles which result in the one-by-one delivery, to an off-bearing conveyor, of successive logs. The discs in each pair are each formed with a uniquely configured perimeter portion characterized by multiple angularly oriented chord stretches which function, as will be described below, to perform positive log separation.
While different mills may be set up to handle different ranges of log diameters, the apparatus of the invention, as described herein, has been designed to handle logs whose diameters fall within the range from about 31/2-inches to about 21-inches. Also, while different mills might be intended for the handling of logs having different maximum lengths, the apparatus herein discussed is designed to handle logs having lengths up to about 20-feet.
With respect to the capability of the instant apparatus to perform positive log separation, probably the most critical condition is that encountered where two successive side-by-side logs each has substantially the smallest diameter (31/2-inches herein) expected to be encountered. The chord stretches referred to above which form a critical element in the apparatus of the invention are uniquely shaped and oriented, as will be explained, to assure positive separation under the critical operating condition just described.
Simplicity in the construction of the apparatus of the invention is contributed largely by the fact that all of the operative log-separating discs just mentioned are carried for counter-rotation on only two torque-tube shafts, which are driven through the action of a common air-actuated cylinder. These two shafts are supported on a simple common frame, and are journaled for counter-rotation merely by two sets of end bearings. One of the advantages of using torque-tube shafts, as just indicated, is that they can be made robust, and yet light in weight so as not to be subjected to bending. Further, a two-shaft construction as outlined, obviates the necessity for bearings intermediate the end bearings, and offers a structure which is minimally subject to catching debris.
These and other objects and advantages which are attained by the invention will become more fully apparent as the description which now follows is read in conjunction with the accompanying drawings.